Studies on interferon induction and interferon sensitivity of avian reoviruses

Four strains of avian reovirus were ineffective inducers of interferon (IFN) in chicken kidney (CK) cell cultures. All strains were similar in single-cycle replication curves. At multiplicities of infection between 0.20 and 10 plaque-forming units per cell, IFN was not induced in CK cells. Reovirus did not produce an IFN blocker in CK cells. Attenuated reovirus did induce IFN in aged chicken embryo fibroblast (CEF) cell cultures. By priming cells with a low dose of IFN before infection with reovirus, IFN formation by CEF could be enhanced. Ultraviolet-inactivated avian reovirus was an effective inducer of IFN in both CK and CEK cell cultures. The sensitivity of avian reoviruses (Fahey-Crawley, Reo-25, S-1133, Reo-V) to chicken interferon (Ch-IFN) was studied by the plaque-reduction method. Avian reoviruses were less sensitive to Ch-IFN than was vesicular stomatitis virus or Semliki Forest virus and appeared to be as resistant to IFN as was Newcastle disease virus.